1. Field of the Invention
The present invention relates to a power supply device of a small arms fire control system and a similar military/civilian power supply device, which are driven using a battery and an electric double layer capacitor (hereinafter, referred to as a “supercapacitor”) and require instant high power.
2. Background of the Related Art
In general, a small arms fire control system must be driven using only a battery for portability and must have a main control board and an infrared processing board driven within a maximum continuous discharging current range of the battery. The fire control system must also be able to supply power to devices requiring an instant high power necessary for the driving of a laser range finder module and an infrared shutter and energy charging of a fuse setter within a range of the greatest pulse discharging current.
In a state where an average current of 1.5 A is continuously supplied from the battery to the system, current of 1.5 A must be supplied for a specific time (for example, 0.5 second) every 5-second cycle. To this end, it is required to use a battery having a sufficiently high capacity or a supercapacitor that can compensate for an instant high current.
Thus, the most appropriate method of stably supplying power to a small arms system, which is driven by a battery and portable, is to design a power supply device having a combination of the battery and the supercapacitor.
However, this method also entails a problem in that excessive current is needed by the battery upon the initial charging of the capacitor, thereby causing damage to the battery.
Therefore, the existing power supply devices using the battery and the supercapacitor employ a current limit circuit or a chip in order to prevent excessive current required to charge the capacitor. The current limit circuit or chip always limits the current to a fixed current value irrespective of the power supply state of a system. Accordingly, an efficient use of the system power is inevitable and, therefore, there occurs a problem in that the charging time of the supercapacitor is lengthened.
In particular, this problem is more important in such a small arms fire control system, wherein a normal operation of the system is guaranteed within a constant battery capacity and accurate power control is needed in order to stably supply an instant high power necessary for driving of a laser range finder module and an infrared shutter and energy charging of a fuse setter.
Particularly, in the case of a small arms fire control system that is driven using a single battery so as to minimize the size of an overall system, required power must be stably supplied to loads requiring voltage, which is several times to several hundreds of times greater than the battery voltage. To this end, a step-up DC-DC boost converter for boosting the battery voltage and the supercapacitor for supplying an instant high power are necessarily required.
Furthermore, in the case of a load that stably requires a voltage of several hundreds of volts for several milliseconds, such as the laser range finder module, a battery voltage must be primarily boosted using the step-up DC-DC boost converter and then supplied to the step-up DC-DC boost converter for the laser range finder module. At this time, if the supercapacitor is fully charged by the primarily boosted voltage, a high initial inrush current is generated, which may give great damage to the supercapacitor and other components. When considering that an average efficiency of the step-up DC-DC boost converter reaches 80 to 85%, there also occurs a problem in that the charging efficiency is reduced.